| 1. |
- Arjmand, Doghonay, et al.
(författare)
-
Atomistic-continuum multiscale modelling of magnetisation dynamics at non-zero temperature
- 2018
-
Ingår i: Advances in Computational Mathematics. - : Springer Science and Business Media LLC. - 1019-7168 .- 1572-9044. ; 44:4, s. 1119-1151
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, a few problems related to multiscale modelling of magnetic materials at finite temperatures and possible ways of solving these problems are discussed. The discussion is mainly centred around two established multiscale concepts: the partitioned domain and the upscaling-based methodologies. The major challenge for both multiscale methods is to capture the correct value of magnetisation length accurately, which is affected by a random temperature-dependent force. Moreover, general limitations of these multiscale techniques in application to spin systems are discussed.
|
|
| 2. |
- Arjmand, Doghonay, et al.
(författare)
-
Modelling long-range interactions in multiscale simulations of ferromagnetic materials
- 2020
-
Ingår i: Advances in Computational Mathematics. - New York : Springer. - 1019-7168 .- 1572-9044. ; 46:1
-
Tidskriftsartikel (refereegranskat)abstract
- Atomistic-continuum multiscale modelling is becoming an increasingly popular tool for simulating the behaviour of materials due to its computational efficiency and reliable accuracy. In the case of ferromagnetic materials, the atomistic approach handles the dynamics of spin magnetic moments of individual atoms, while the continuum approximations operate with volume-averaged quantities, such as magnetisation. One of the challenges for multiscale models in relation to physics of ferromagnets is the existence of the long-range dipole-dipole interactions between spins. The aim of the present paper is to demonstrate a way of including these interactions into existing atomistic-continuum coupling methods based on the partitioned-domain and the upscaling strategies. This is achieved by modelling the demagnetising field exclusively at the continuum level and coupling it to both scales. Such an approach relies on the atomistic expression for the magnetisation field converging to the continuum expression when the interatomic spacing approaches zero, which is demonstrated in this paper.
|
|
| 3. |
- Méndez, Édgar, et al.
(författare)
-
Multiscale approach for magnetization dynamics : unraveling exotic magnetic states of matter
- 2020
-
Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 2:1
-
Tidskriftsartikel (refereegranskat)abstract
- Crystallographic lattice defects strongly influence dynamical properties of magnetic materials at both microscopic and macroscopic length scales. A multiscale approach to magnetization dynamics, which is presented in this paper, accurately captures such effects. The method is illustrated using examples of systems with localized, nontrivial topological properties, e.g., in the form of skyrmions and domain walls that interact with lattice dislocations. Technical aspects of the methodology involve multiscale magnetization dynamics that connect atomistic and continuum descriptions. The technique is capable of solving the Landau-Lifshitz-Gilbert equations efficiently in two regions of a magnetic material—the mesoscopic and the atomistic regions, which are coupled in a seamless way. It is demonstrated that this methodology allows simulating realistically sized magnetic skyrmions interacting with material defects and complex physical effects.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Poluektov, Mikhail, et al.
(författare)
-
Scale transitions in magnetisation dynamics
- 2016
-
Ingår i: Communications in Computational Physics. - : Global Science Press. - 1815-2406 .- 1991-7120. ; 20, s. 969-988
-
Tidskriftsartikel (refereegranskat)abstract
- Multiscale modelling is a powerful technique, which allows for computational efficiency while retaining small-scale details when they are essential for understanding a finer behaviour of the studied system. In the case of materials modelling, one of the effective multiscaling concepts is domain partitioning, which implies the existence of an explicit interface between various material descriptions, for instance atomistic and continuum regions. When dynamic material behaviour is considered, the major problem for this technique is dealing with reflections of high frequency waves from the interface separating two scales. In this article, a new method is suggested, which overcomes this problem for the case of magnetisation dynamics. The introduction of a damping band at the interface between scales, which absorbs high frequency waves, is suggested. The idea is verified using a number of one-dimensional examples with fine/coarse scale discretisation of a continuum problem of spin wave propagation. This work is the first step towards establishing a reliable atomistic/continuum multiscale transition for the description of the evolution of magnetic properties of ferromagnets.
|
|
| 7. |
|
|
